1. Field of the Invention
This invention relates to puncturing devices for tomography.
2. Description of the Related Art
Tomography, such as MRI (magnetic resonance imaging), operating in real time, and CT (computed tomography), is often used in imaging for medicine.
Understood by tomography in connection with the present invention should be imaging methods used in medicine, in particular MRI (magnetic resonance imaging), operating in real time, and CT (computed tomography).
Punctures monitored through tomography entail various problems and difficulties. The spatial relations in the imaging installation are very tight, whereby the dimensions of a puncturing device are limited. During MRI, not just any desired materials can be brought into the magnetic field, in particular no ferromagnetic materials. The physician follows the puncturing needle on the picture screen, and can only see this needle as long as it is located at least close to the cutting plane, which is determined in the case of MRI by the magnetic field, and in the case of CT by the X-rays. Thus it can very well happen that the puncture needle is visible in the region of the puncture site, but not its point, however, since its point is located in front of, or behind, the picture plane. It is easy to imagine the difficulties that confront the physician in such a situation. Upon puncturing of the puncture needle, in particular in the abdominal region of a patient, the tissue can first bend greatly inward, whereby a sighted organ to be punctured or a tumour can slip away sideways.
Various devices are known which serve the precise positioning of a patient in a tomographic installation, and which therefore also find application in punctures. Several of these devices operate with optical measurement of reference points placed on the body of the patient. These reference points can be markings drawn, pasted or also projected on the skin. The last-mentioned can be generated, for example, by means of a laser beam. All these optical devices have in common that they are very consuming and therefore expensive. Moreover, their dimensions and their arrangement in the tomographic installation can impede the physician during a puncture, or the physician can disturb the functioning of the positioning device if he inadvertently interrupts the measuring beams. A simple and precise way of guiding the needle is not available in any of the devices of this kind.
The printed patent specification U.S. Pat No. 4,826,487 relates to an alignment button for a stereotaxic plug and method of using the same. The plug can bear a thread on its outer circumference, and is intended to be placed in the cranium of a patient. It bears a plurality of axial bores disposed in a particular pattern, of which a first group is designed as a guide cannulae for surgical instruments. A second group of axial bores is designed as marker bores, the bores containing a contrast medium depending upon the respective tomography. Gold is proposed as the contrast medium for pictures with X-rays, and for MRI images water or lipids. After insertion of the plug, the scalp is pulled over it and sutured in order to keep the risk of infection as minimal as possible. The alignment button contains cannulae and marker bores disposed in a pattern identical to the pattern of the plug. It is precisely aligned with the plug in a corresponding imaging device, and then sewn to the scalp. With this system both an exact locating of the puncture site by means of a tomographic method as well as a precise guiding of a surgical instrument, for example a puncture needle, are possible. However, this system can only be used sensibly for surgical interventions repeated at temporal intervals, in particular in the skull, and is not suitable for single punctures. Indicated in the printed patent specification is that the alignment button can also be used alone. The guiding of the needle is thereby omitted, however, so that although the puncture site is determinable by means of the alignment button, the direction of puncture of the needle is not.
The printed patent specification U.S. Pat. No. 5,178,146 relates to a system for aligning a patient for use of MRI or other imaging methods. The system includes in particular a cuboidal box to be placed spaced apart from the region of the body of the patient to be examined, in the walls of which box tubes, filled with a contrast medium, have been placed in a particular pattern. Indicated as contrast medium for MRI is, for example, a gadolinium compound, and for CT, a barium compound. Both tubes disposed in a right-angle pattern as well as tubes disposed running diagonally are provided. The latter generate shadows in the picture which displace themselves in the picture plane when the box is moved through the field. From the mutual position of these shadows the physician can discern whether the patient has assumed the desired position in the imaging installation. This system is intended in particular to bring into line pictures generated by means of MRI with pictures generated by other means. For this purpose the contrast medium in the tubes is exchangeable. One application example is in radiation therapy in which, for example, a tumour is first located by means of MRI, and subsequently irradiated with X-rays. The precise position for irradiation is then reached when the pattern generated by the tubes on the CT picture coincides with that on the previously generated MRI picture. Although it is mentioned in the printed patent specification that the system can also find application for punctures, there are no indications of a needle guide. Above and beyond that, it is apparent that the said box can additionally impede the doctor when puncturing.
It is the objective of the present invention to create a puncturing device which can be manufactured simply and inexpensively, and can be operated safely and reliably. Another objective of the invention is to provide a puncturing device with small dimensions, and which therefore is usable with the narrow space relations that prevail in the imaging installation. A further objective of the invention consists in creating a puncturing device which can be made of materials that cause no interference during the respective tomographic procedure. Furthermore the invention has the objective of providing the physician with a puncturing device with which the puncture needle can be aligned precisely with the picture plane, so that this needle can be observed at any time on the picture screen from the puncture site to the point. Finally, with the puncturing device according to the invention the respective bodily region of the patient should be able to be compressed before insertion of the puncture needle, so that the indentation of this region and thereby a slipping away of the organ or tumour to be punctured can be minimized. These objectives are achieved through the present invention.
In some embodiments of the present invention, a puncturing device is provided that comprises a body with substantially the shape of a cuboid having a base area parallel to a longitudinal axis of the body. The base area is configured to be placed upon the skin of a patient. A guide means cuts the base area at a right angle, and there are at least two elongated hollow spaces disposed at right angles to the longitudinal axis of the body, but not parallel to the guide means and not parallel to one another.
A further object of the invention consists in proposing a puncturing device which can be removed after insertion of the puncture needle into the body of a patient, without the puncture needle having to be pulled out for this purpose. This object is achieved through a puncturing device having the features of claim 7.
Further special embodiments of the puncturing device according to the invention are described in the dependent claims.
The invention will be described more closely in the following with reference to the embodiments presented in the drawings.